JP2015064309A - Magnetic sensor using polygonal prism magnet - Google Patents
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Abstract
Description
本発明は、バイアス永久磁石および磁気抵抗効果素子を用いた磁気センサに関する。 The present invention relates to a magnetic sensor using a bias permanent magnet and a magnetoresistive effect element.
磁場の変化に応じて電圧・電流・抵抗値が変化する特性を利用した磁気センサは、携帯電話やノートパソコンなどの開閉部に用いられる非接触スイッチ、カードリーダーや紙幣識別装置に使用される磁気ヘッド、電子コンパスやＧＰＳ補正機能として利用される地磁気センサ、エンジン回転数検知や車輪角度検出に用いられる回転センサや角度センサなど種々の用途に適用されている。磁気センサの種類として、ホール素子、磁気抵抗効果素子、磁気インピーダンス（ＭＩ）素子、ＳＱＵＩＤ（超伝導量子素子）などがある。たとえば、磁場の強さにより電気抵抗値が変化する現象を用いた磁気抵抗効果素子（以下、ＭＲ素子とも記載）は、高感度で磁気ヘッド技術を応用できるので、磁気インクを印刷した紙幣や有価証券等のパターン検出や識別に用いられている。 Magnetic sensors that use voltage, current, and resistance values to change according to changes in the magnetic field are magnetic switches that are used in contactless switches, card readers, and banknote recognition devices used in mobile phones and notebook PCs. The present invention is applied to various applications such as a head, an electronic compass, a geomagnetic sensor used as a GPS correction function, a rotation sensor and an angle sensor used for engine rotation speed detection and wheel angle detection. Examples of the magnetic sensor include a Hall element, a magnetoresistive effect element, a magnetic impedance (MI) element, and a SQUID (superconducting quantum element). For example, a magnetoresistive effect element (hereinafter also referred to as an MR element) using a phenomenon in which an electric resistance value changes depending on the strength of a magnetic field can be applied to a magnetic head technology with high sensitivity. It is used for pattern detection and identification of securities.
図６は、従来の磁気センサチップおよびバイアス永久磁石から構成される磁気センサを用いた磁気インク検出方法を示す図である。四角形状の永久磁石１０２の中心位置付近.上方に磁気センサチップ１０１が永久磁石１０２の上面に平行に配置され、永久磁石１０２は磁気センサチップ１０１に形成されたＭＲ素子１０４にバイアス磁場を与えている。通常、水平方向磁場を検知するＭＲ素子には、バイアス磁場として垂直方向磁場Ａ０ではなく、水平方向磁場を有する曲線磁場Ａ１が作用している。磁気センサチップ１０１は永久磁石１０２が作るバイアス磁場の垂直方向磁場Ａ０の直上付近に配置され、磁気センサチップ１０１上に搭載されたＭＲ素子１０４が磁気インク１０３を検出する方向（磁気インク検出方向）Ｂは垂直方向磁場Ａ０に直角となっている。磁気インク１０３は磁気センサチップ１０１の上方を移動し、磁気インク１０３の移動方向Ｃは磁気インク検出方向Ｂと一致している。磁気インク１０３が移動してＭＲ素子に作用している曲線磁場Ａ１の近傍に達して横切るとき磁場Ａ１が変動するので、ＭＲ素子に抵抗変化が生じる。 FIG. 6 is a diagram showing a magnetic ink detection method using a magnetic sensor composed of a conventional magnetic sensor chip and a bias permanent magnet. Near the center position of the rectangular permanent magnet 102. The magnetic sensor chip 101 is arranged in parallel to the upper surface of the permanent magnet 102, and the permanent magnet 102 applies a bias magnetic field to the MR element 104 formed on the magnetic sensor chip 101. Yes. Normally, a curved magnetic field A1 having a horizontal magnetic field is acting as a bias magnetic field on the MR element that detects the horizontal magnetic field, not the vertical magnetic field A0. The magnetic sensor chip 101 is arranged in the vicinity immediately above the vertical magnetic field A0 of the bias magnetic field created by the permanent magnet 102, and the MR element 104 mounted on the magnetic sensor chip 101 detects the magnetic ink 103 (magnetic ink detection direction). B is perpendicular to the vertical magnetic field A0. The magnetic ink 103 moves above the magnetic sensor chip 101, and the moving direction C of the magnetic ink 103 coincides with the magnetic ink detection direction B. Since the magnetic field A1 fluctuates when the magnetic ink 103 moves and reaches and crosses the vicinity of the curved magnetic field A1 acting on the MR element, a resistance change occurs in the MR element.
図７は、水平方向磁場とＭＲ素子の抵抗変化との関係を示すグラフである。
図７（ａ）は水平方向磁場がゼロ、つまり、垂直方向磁場Ａ０のみにおけるＭＲ素子の抵抗変化を示す。このとき、動作点はＬ０の位置になるため、検出磁場Ｈｘに対する抵抗変化ΔＲは極めて小さくなってしまう。図７（ｂ）はある程度の水平方向磁場Ｈｘ１がバイアス磁場として作用するように、ＭＲ素子１０４を垂直方向磁場Ａ０の位置から水平方向にｘ１だけずらして配置したとき（水平方向磁場を有する曲線磁場Ａ１が作用する場合）のＭＲ素子の抵抗変化を示す。このとき、動作点はＬ１の位置となり、その動作点Ｌ１の近傍では、磁場変化に対してある程度の傾き（この傾きの大きさが感度である）を有しているため、磁場変化Ｈｘによる抵抗変化ΔＲはかなり大きくなる。
FIG. 7 is a graph showing the relationship between the horizontal magnetic field and the resistance change of the MR element.
FIG. 7A shows the resistance change of the MR element when the horizontal magnetic field is zero, that is, only in the vertical magnetic field A0. At this time, since the operating point is at the position L0, the resistance change ΔR with respect to the detected magnetic field Hx becomes extremely small. FIG. 7B shows a case where the MR element 104 is arranged so as to be shifted by x1 in the horizontal direction from the position of the vertical magnetic field A0 so that a certain amount of horizontal magnetic field Hx1 acts as a bias magnetic field (curved magnetic field having a horizontal magnetic field). The resistance change of the MR element when A1 acts) is shown. At this time, the operating point is at the position L1, and in the vicinity of the operating point L1, there is a certain degree of inclination with respect to the magnetic field change (the magnitude of this inclination is sensitivity). The change ΔR becomes considerably large.
従って、水平方向磁場を検知するＭＲ素子は、垂直方向磁場の直上（水平方向磁場がゼロになる位置）ではなく、その位置から少しずらしてある程度の水平方向の磁場が作用する磁場に配置し、ＭＲ素子に適切なバイアス磁場を与えられるようにする。
図８は四角形状のバイアス磁石とＭＲ素子との位置関係を示し、ＭＲ素子を複数配置した場合の構成例を示す。図８（ａ）は磁石２３の横方向から見た位置関係を示す正面図で、図８（ｂ）はバイアス磁石２３の上方から見た位置関係を示す平面図である。図８（ａ）に示すように、バイアス磁石２３の磁石中心線Ｖ４に対して直角方向のライン（平面）Ｃ１上にＭＲ素子２４が配置されている。実際には、Ｃ１は実装基板の表面であり、その表面に複数のＭＲ素子２４が搭載されている。ＭＲ素子２４はＣ１方向に対する磁場、すなわち水平方向磁場の変化に対して抵抗が変化するように配置されている。図７において示したように水平方向磁場がゼロとなる位置よりも少しずらした所（ラインＣ２）にＭＲ素子２４は配置される。
Therefore, the MR element that detects the horizontal magnetic field is not directly above the vertical magnetic field (the position where the horizontal magnetic field becomes zero), but is slightly shifted from that position and is arranged in a magnetic field where some horizontal magnetic field acts, An appropriate bias magnetic field is applied to the MR element.
FIG. 8 shows the positional relationship between the square-shaped bias magnet and the MR element, and shows a configuration example when a plurality of MR elements are arranged. FIG. 8A is a front view showing the positional relationship of the magnet 23 as viewed from the lateral direction, and FIG. 8B is a plan view of the positional relationship as viewed from above the bias magnet 23. As shown in FIG. 8A, the MR element 24 is arranged on a line (plane) C1 perpendicular to the magnet center line V4 of the bias magnet 23. Actually, C1 is the surface of the mounting substrate, and a plurality of MR elements 24 are mounted on the surface. The MR element 24 is arranged such that the resistance changes with respect to the change of the magnetic field in the C1 direction, that is, the horizontal magnetic field. As shown in FIG. 7, the MR element 24 is arranged at a position slightly shifted from the position where the horizontal magnetic field becomes zero (line C2).
しかしながら、図８に示した四角形状（断面が長方形の平板状）のバイアス磁石（以下、四角磁石とも記載）において、磁石の材質や着磁の仕方などの製造バラツキなどにより水平方向磁場がゼロになる位置は、バイアス磁石２３の磁石中心線Ｖ４と一致せず、一直線とはならない。図９は四角形状のバイアス磁石の磁場を示す図である。図９（ａ）は理想的な状態で磁石が磁化されたときの磁場を示す図である。図の曲線が磁力線でバイアス永久磁石の作る磁場の状態を示す。上部がＮ極で下部がＳ極の四角形状の磁石２１を横方向に見た磁場である。理想的には磁石２１の中心Ｏにおいて磁力線軸Ｅ１が磁石２１の上面に対して９０度方向になり、磁力線軸Ｅ１方向が垂直磁場Ｖｏ方向と一致する。従って、水平方向磁場がゼロになるポイントＰ１は磁石２１の中心Ｏと一致する。尚、磁力線軸とは、磁石中心位置における磁力線の方向を示す軸である。 However, the horizontal magnetic field of the bias magnet (hereinafter also referred to as a square magnet) shown in FIG. 8 is zero due to variations in the material of the magnet and the method of magnetization. This position does not coincide with the magnet center line V4 of the bias magnet 23 and does not form a straight line. FIG. 9 is a diagram showing the magnetic field of a square bias magnet. FIG. 9A shows a magnetic field when the magnet is magnetized in an ideal state. The curve in the figure shows the state of the magnetic field created by the bias permanent magnet with the magnetic field lines. This is a magnetic field of a rectangular magnet 21 having an N pole at the top and an S pole at the bottom as viewed laterally. Ideally, the magnetic force axis E1 is 90 degrees with respect to the upper surface of the magnet 21 at the center O of the magnet 21, and the direction of the magnetic force axis E1 coincides with the direction of the vertical magnetic field Vo. Therefore, the point P 1 at which the horizontal magnetic field becomes zero coincides with the center O of the magnet 21. In addition, a magnetic force line axis | shaft is an axis | shaft which shows the direction of the magnetic force line in a magnet center position.
しかし、磁石の材質や着磁の仕方などの製造バラツキ等によって磁力線軸は理想角度から傾いてしまう。たとえば、図９（ｂ）は磁石２１の中心Ｏにおける磁力線軸Ｅ２が図の左側に少し（１０度）傾いた場合の磁場の状態を示している。このとき垂直磁場Ｖoの位置は磁石２１の中心Ｏから図の右側にずれた所に発生する。すなわち、水平方向磁場がゼロになるポイントＰ２は磁石２１の中心Ｏから右側に矢印で示す分（ｐ２）だけずれてしまう。また、図９（ｃ）は磁石２１の中心Ｏにおける磁力線軸Ｅ３が図の右側に少し（１０度）傾いた場合の磁場の状態を示している。このとき垂直磁場Ｖｏの位置は磁石２１の中心Ｏから図の左側にずれた所に発生する。すなわち、水平方向磁場がゼロになるポイントＰ３は磁石２１の中心Ｏから左側に矢印で示す分（ｐ３）だけずれてしまう。 However, the magnetic field axis is inclined from the ideal angle due to manufacturing variations such as the material of the magnet and the method of magnetization. For example, FIG. 9B shows the state of the magnetic field when the magnetic force axis E2 at the center O of the magnet 21 is slightly inclined (10 degrees) to the left side of the figure. At this time, the position of the vertical magnetic field Vo is generated at a position shifted from the center O of the magnet 21 to the right side of the drawing. That is, the point P2 at which the horizontal magnetic field becomes zero is shifted from the center O of the magnet 21 by the amount (p2) indicated by the arrow on the right side. FIG. 9C shows the state of the magnetic field when the magnetic force axis E3 at the center O of the magnet 21 is slightly inclined (10 degrees) to the right side of the figure. At this time, the position of the vertical magnetic field Vo is generated at a position shifted from the center O of the magnet 21 to the left side of the drawing. That is, the point P3 at which the horizontal magnetic field becomes zero is shifted from the center O of the magnet 21 by the amount (p3) indicated by the arrow on the left side.
このように、一般に従来の磁気センサに用いられる四角形状のバイアス磁石において、製造バラツキなどにより水平方向磁場がゼロになる位置は磁石の中心からずれてしまう。つまり、図８での水平方向磁場がゼロになる位置は、バイアス磁石２３の中心であるラインＶ４（バイアス磁石２３の中央ライン）からずれてしまい、実際には曲線Ｖ５のようになってしまう。 As described above, in a rectangular bias magnet generally used for a conventional magnetic sensor, the position where the horizontal magnetic field becomes zero is shifted from the center of the magnet due to manufacturing variation or the like. That is, the position at which the horizontal magnetic field in FIG. 8 becomes zero shifts from the line V4 that is the center of the bias magnet 23 (the center line of the bias magnet 23), and actually becomes a curve V5.
よって、水平方向磁場がゼロになる位置がバイアス磁石２３の中心であるとして適切なバイアス磁場が与えられるように、ラインＶ４から少しずらした直線状のラインＣ２に沿って、アレイ上にＭＲ素子２４を配置したとしても、配置された多数のＭＲ素子において、水平方向磁場がゼロになるＭＲ素子もあれば、逆方向のバイアス磁場がかかってしまうＭＲ素子もある。従って、図７から分かるように、各ＭＲ素子の抵抗値変化量が大きくばらつき、各ＭＲ素子の感度も一定にならず大きくばらつく。特に、多数のＭＲ素子からなるＭＲ素子アレイではさらに磁気センサの感度がばらついてしまう。１個のＭＲ素子だけ、あるいは少数のＭＲ素子を搭載するだけなら、水平方向磁場がゼロになる点を測定した後にＭＲ素子を実装する方法もあるが、実装時間が大幅に長くなりコスト高となり実用的ではない。 Therefore, the MR element 24 is arranged on the array along the straight line C2 slightly shifted from the line V4 so that an appropriate bias magnetic field is given assuming that the position where the horizontal magnetic field becomes zero is the center of the bias magnet 23. Even in the case of the arrangement, in many of the arranged MR elements, there are MR elements in which the horizontal magnetic field becomes zero, and there are MR elements in which a bias magnetic field in the reverse direction is applied. Therefore, as can be seen from FIG. 7, the amount of change in the resistance value of each MR element varies greatly, and the sensitivity of each MR element is not constant and varies greatly. In particular, in the MR element array composed of a large number of MR elements, the sensitivity of the magnetic sensor further varies. If only one MR element or a small number of MR elements are mounted, there is a method of mounting the MR element after measuring the point where the horizontal magnetic field becomes zero. However, the mounting time is significantly increased and the cost is increased. Not practical.
本発明は、従来の磁気センサに用いられている四角形状とする長方形型平板形状のバイアス永久磁石の代わりに断面上部が三角形である多角柱形状のバイアス永久磁石を磁気センサに用いるものであり、具体的には以下の特徴を有する。
（１）本発明は、磁気抵抗効果素子およびバイアス永久磁石を用いた磁気センサにおいて、前記永久磁石は多角柱形状であって、その多角柱形状の断面上部が三角形状であり、その三角形状の上部頂点を結ぶ稜線に対してＮ極またはＳ極が着磁されることを特徴とし、前記磁気抵抗効果素子は前記永久磁石の前記稜線の上方に配置されることを特徴とする磁気センサである。
（２）本発明は、（１）に加えて、前記磁気抵抗効果素子は前記永久磁石の前記稜線に対する着磁方向と直交する平面上に配置されることを特徴とし、さらに前記磁気抵抗効果素子は複数であり、複数の磁気抵抗効果素子は前記永久磁石の前記稜線に対して平行な直線上に配置されることを特徴とする。
（３）本発明は、（１）または（２）に加えて、前記磁気抵抗効果素子は前記稜線の両側に配置され、さらに、前記稜線の両側に配置された磁気抵抗効果素子は前記稜線に対して対称な位置に配置されることを特徴とする。
（４）本発明は、上記に加えて、前記磁気抵抗効果素子は、非飽和領域内に配置されることを特徴とし、さらに、前記永久磁石の断面上部の三角形状は二等辺三角形を有し、前記上部頂点が二等辺三角形の頂点であることを特徴とする。
The present invention uses, in place of a rectangular flat plate-shaped bias permanent magnet having a rectangular shape used in a conventional magnetic sensor, a polygonal column-shaped bias permanent magnet having a triangular cross-section upper portion for a magnetic sensor, Specifically, it has the following characteristics.
(1) The present invention relates to a magnetic sensor using a magnetoresistive effect element and a bias permanent magnet, wherein the permanent magnet has a polygonal column shape, and the upper section of the polygonal column shape is triangular, and the triangular shape The magnetic sensor is characterized in that an N-pole or an S-pole is magnetized with respect to a ridge line connecting the upper vertices, and the magnetoresistive element is disposed above the ridge line of the permanent magnet. .
(2) In addition to (1), the present invention is characterized in that the magnetoresistive effect element is disposed on a plane perpendicular to the magnetization direction of the permanent magnet with respect to the ridge line, and further the magnetoresistive effect element Is a plurality, and the plurality of magnetoresistive elements are arranged on a straight line parallel to the ridgeline of the permanent magnet.
(3) In addition to (1) or (2), in the present invention, the magnetoresistive effect element is disposed on both sides of the ridge line, and the magnetoresistive effect element disposed on both sides of the ridge line is disposed on the ridge line. They are arranged at symmetrical positions.
(4) In addition to the above, the present invention is characterized in that the magnetoresistive element is disposed in a non-saturated region, and the triangular shape of the upper part of the cross section of the permanent magnet has an isosceles triangle. The upper vertex is an isosceles triangular vertex.
本発明の磁気センサに用いる断面上部が三角形である多角柱形状のバイアス永久磁石は、従来の磁気センサに用いられている四角形状のバイアス永久磁石よりも、水平方向磁場がゼロになる点のバラツキが小さいので、それぞれの磁気抵抗効果素子に適切なバイアス磁界をかけることができ、各磁気抵抗効果素子の感度を一定に揃えることができる。特にアレイ状に多数の磁気抵抗効果素子を配置した場合にその効果が大きい。また、断面上部が三角形である多角柱形状のバイアス永久磁石は、個体間による水平方向磁場がゼロになる点のバラツキも小さいので、安定した磁気特性を有する磁気センサを作製できる。 The polygonal pole-shaped bias permanent magnet used in the magnetic sensor of the present invention has a triangular cross-section upper portion, and the variation in the horizontal magnetic field is zero compared to the square-shaped bias permanent magnet used in the conventional magnetic sensor. Therefore, an appropriate bias magnetic field can be applied to each magnetoresistive effect element, and the sensitivity of each magnetoresistive effect element can be made uniform. The effect is particularly great when a large number of magnetoresistive elements are arranged in an array. In addition, since the polygonal prism-shaped bias permanent magnet having a triangular upper section has little variation in the horizontal magnetic field between individuals, a magnetic sensor having stable magnetic characteristics can be manufactured.
本発明は、従来の磁気センサに用いられている長方形型平板形状のバイアス永久磁石（以下、四角磁石ともいう）の代わりに断面上部が三角形である多角柱形状のバイアス永久磁石を磁気センサに用いることによって、水平方向磁場がゼロとなるポイント（以下、水平方向磁場ゼロ点ともいう）の変動を小さくするものである。 The present invention uses, in place of a rectangular flat plate-shaped bias permanent magnet (hereinafter also referred to as a square magnet) used in a conventional magnetic sensor, a polygonal column-shaped bias permanent magnet whose upper section is a triangle for the magnetic sensor. Thus, the fluctuation of the point at which the horizontal magnetic field becomes zero (hereinafter also referred to as the horizontal magnetic field zero point) is reduced.
まず、本発明の磁気センサに用いるバイアス永久磁石として、断面が三角形である三角柱形状のバイアス永久磁石（以下、三角磁石ともいう）を用いた場合の実施形態について示す。
図１は、本発明の磁気センサに用いられる三角磁石の作る磁場をシミュレーションして表現した図である。図１に示す三角磁石１は、三角柱形状の断面が二等辺三角形であり、頂点側がN極でその対辺（以下、底辺）側がS極となっている。図１に示す磁場の状態は、頂点側から底辺側に向かう磁場分布であり、図１に示す細い実線（曲線）は磁力線を表す。図１（ａ）は理想的に作製された三角磁石の磁場を示す。ここで理想的にとは、磁石の材質が均一に分布し、磁区も均一に揃い、着磁等の製造バラツキもなく、さらに形状も正確に作製された場合等を意味する。三角磁石１の頂点Ｏおよび底辺の中点を通る中線（垂線と一致する）Ｍ１に対して磁石の材質や着磁状態等の磁場を発生する要素が均一に形成されている（理想的な状態）ので、三角磁石１の磁場は中線Ｍ１に対して対象となっている。このＭ１は幾何学的な磁石中心線でもある。頂点Ｏから出る磁力線（すなわち、磁石中心位置における磁力線であり、これを以下、磁力線軸と称する）Ｅ１は中線Ｍ１上にあり、垂直磁場を示している。従って、頂点Ｏにおける水平（方向）磁場（三角磁石１の底辺に平行な方向の磁場、あるいは中線Ｍ１または磁石中心線に垂直な方向の磁場）はゼロ（０）であり、この水平方向磁場ゼロ点Ｐ１は頂点Ｏと一致する。
First, an embodiment in which a triangular prism-shaped bias permanent magnet (hereinafter also referred to as a triangular magnet) having a triangular cross section is used as the bias permanent magnet used in the magnetic sensor of the present invention will be described.
FIG. 1 is a diagram representing a magnetic field created by a triangular magnet used in the magnetic sensor of the present invention by simulation. The triangular magnet 1 shown in FIG. 1 has an isosceles triangular cross section in the shape of a triangular prism, and has an N pole on the apex side and an S pole on the opposite side (hereinafter referred to as the bottom side). The state of the magnetic field shown in FIG. 1 is a magnetic field distribution from the top side to the bottom side, and the thin solid line (curve) shown in FIG. FIG. 1A shows the magnetic field of an ideally produced triangular magnet. Here, “ideal” means a case where the magnet material is uniformly distributed, the magnetic domains are evenly aligned, there is no manufacturing variation such as magnetization, and the shape is accurately manufactured. Elements that generate a magnetic field such as a magnet material and a magnetized state are uniformly formed with respect to a midline (corresponding to a perpendicular) M1 passing through the vertex O and the midpoint of the base of the triangular magnet 1 (ideal State), the magnetic field of the triangular magnet 1 is targeted with respect to the middle line M1. This M1 is also a geometrical magnet center line. A magnetic field line emanating from the vertex O (that is, a magnetic field line at the magnet center position, hereinafter referred to as a magnetic field line axis) E1 is on the middle line M1 and indicates a vertical magnetic field. Accordingly, the horizontal (direction) magnetic field at the vertex O (the magnetic field in the direction parallel to the bottom of the triangular magnet 1 or the magnetic field in the direction perpendicular to the midline M1 or the magnet center line) is zero (0). The zero point P1 coincides with the vertex O.
しかし実際の磁石では磁石の材質や着磁状態等の製造条件のバラツキなどによって理想的な状態で作製することは難しいので、磁力線軸は少し傾いて形成される。図１（ｂ）は、磁力線軸Ｅ２が約１０度（中線Ｍ１に対して）左側へ傾いた時の磁力線の状態を示す図である。この磁力線状態は理想的な状態と異なっており、中線Ｍ１に対して非対称になっている。この結果、水平方向磁場ゼロ点Ｐ２は中線Ｍ１の右側に少しずれてしまい、三角磁石１の頂点Ｏとは一致しない。しかし、そのズレ量は、図９において示した四角磁石の場合に比べるとかなり小さい。また三角磁石の頂点付近における磁力線の分布状態も理想的な状態からの変化が小さい。 However, since an actual magnet is difficult to be manufactured in an ideal state due to variations in manufacturing conditions such as a magnet material and a magnetized state, the magnetic field axis is formed with a slight inclination. FIG. 1B is a diagram showing a state of magnetic lines of force when the magnetic line E2 is tilted to the left by about 10 degrees (relative to the middle line M1). This line of magnetic force is different from the ideal state and is asymmetric with respect to the middle line M1. As a result, the horizontal magnetic field zero point P2 is slightly shifted to the right side of the middle line M1, and does not coincide with the vertex O of the triangular magnet 1. However, the amount of deviation is considerably smaller than that of the square magnet shown in FIG. In addition, the distribution state of the magnetic field lines near the apex of the triangular magnet is small from the ideal state.
図１（ｃ）は、磁力線軸Ｅ３が約１０度（中線Ｍ１に対して）右側へ傾いた時の磁力線の状態を示す図である。この磁力線状態は理想的な状態と異なっており、中線Ｍ１に対して非対称になる。この結果、水平方向磁場ゼロ点Ｐ３は中線Ｍ１の左側に少しずれてしまい、三角磁石１の頂点Ｏとは一致しない。しかし、そのズレ量は、図９において示した四角磁石の場合に比べるとかなり小さい。また三角磁石の頂点付近における磁力線の分布状態も理想的な状態からの変化も小さい。このように、実際の三角磁石においては、水平方向磁場ゼロ点の磁石中心からのズレはかなり小さくなっている。尚、図１においては頂点側をＮ極とした場合について説明したが、頂点側をＳ極、底辺側をＮ極とした場合においても、磁場の向きが逆になるだけであるから、上記と同様であり、水平方向磁場ゼロ点の磁石中心からのズレはかなり小さくなる。 FIG. 1C is a diagram illustrating a state of magnetic lines of force when the magnetic line E3 is tilted to the right by about 10 degrees (relative to the middle line M1). This magnetic field line state is different from the ideal state, and is asymmetric with respect to the middle line M1. As a result, the horizontal magnetic field zero point P3 is slightly shifted to the left side of the middle line M1, and does not coincide with the vertex O of the triangular magnet 1. However, the amount of deviation is considerably smaller than that of the square magnet shown in FIG. In addition, the distribution state of the magnetic field lines near the apex of the triangular magnet is small from the ideal state. Thus, in an actual triangular magnet, the deviation from the center of the horizontal magnetic field zero point is considerably small. In FIG. 1, the case where the apex side is the N pole has been described. However, even when the apex side is the S pole and the base side is the N pole, only the direction of the magnetic field is reversed. Similarly, the deviation from the magnet center of the horizontal magnetic field zero point is considerably small.
図２は、本発明の磁気センサに用いられる三角磁石と磁気抵抗効果素子の配置状態および水平方向磁場ゼロ点を示す図である。図２（ａ）は横方向断面図（立面図）であり、図２（ｂ）は水平方向透視図（平面図）である。三角磁石１は断面が二等辺三角形であり、頂点側の上方（頂点から一定距離をおいて）にＭＲ素子が配置される。三角磁石１の中線Ｍ２は磁石中心線および垂線（頂角から底辺に下ろした垂直線）である。複数のＭＲ素子２は、中線Ｍ２に垂直な平面Ｃ１上で、かつ三角磁石１の頂点の直上において、中線Ｍ２から少し離して配置される。すなわち、複数のＭＲ素子２は、図２（ｂ）に示すように、中線Ｍ２から距離ｘだけ離れた直線Ｃ２上に配置される。 FIG. 2 is a diagram showing the arrangement of triangular magnets and magnetoresistive elements used in the magnetic sensor of the present invention and the horizontal magnetic field zero point. FIG. 2A is a transverse sectional view (elevated view), and FIG. 2B is a horizontal perspective view (plan view). The triangular magnet 1 has an isosceles triangle cross section, and an MR element is arranged above the apex side (at a certain distance from the apex). The middle line M2 of the triangular magnet 1 is a magnet center line and a perpendicular (a vertical line drawn from the top angle to the bottom side). The plurality of MR elements 2 are arranged on the plane C1 perpendicular to the middle line M2 and slightly above the middle line M2 just above the apex of the triangular magnet 1. That is, as shown in FIG. 2B, the plurality of MR elements 2 are arranged on a straight line C2 that is separated from the middle line M2 by a distance x.
尚、図２（ｂ）に示す直線Ｍ２は図２（ａ）の立面図から平面図へ延長した直線ということで便宜上中線Ｍ２と呼んでいるが、正確には中線ではなく、三角磁石の頂点を結ぶ稜線であり、その線を頂線と名付ける。この頂線と中線はいたる所で垂直に交わっている。また、磁石中心線は、図２（ａ）の立面図でみると中線Ｍ２と一致するが、図２（ｂ）の平面図でみると長方形の対角線の交点からその直上にある頂点を結ぶ線の１本だけである。この１本の磁石中心線はこの位置における断面三角形の中線Ｍ１と一致し、理想的にはこの位置において中線Ｍ１および磁石中心線方向へ垂直方向磁場が生じている。また、図２（ｂ）における中線（頂線）Ｍ２上では理想的には水平方向磁場がゼロとなる。平面Ｃ１が実装基板の表面となる場合は、各ＭＲ素子２は実装基板に個別に実装されるので、中線Ｍ２（正確には頂線Ｍ２）に平行な直線Ｃ２上にＭＲ素子２の中心がくるように配置する。複数のＭＲ素子が１つのチップ（磁気センサチップ）上に形成されている場合は、磁気センサチップが平面Ｃ１となり、磁気センサチップに形成された複数のＭＲ素子２の中心が直線Ｃ２上にくるように磁気センサチップを配置する。尚、ＭＲ素子が１個の場合は、磁石中心線に対して直交する直線Ｃ１上にＭＲ素子を配置するのが、ＭＲ素子の磁気特性を活用する上で最も良い。 The straight line M2 shown in FIG. 2 (b) is a straight line extending from the elevation view of FIG. 2 (a) to the plan view and is referred to as a middle line M2 for convenience. It is a ridge line connecting the vertices of the magnet, and the line is named the top line. The top and middle lines intersect perpendicularly everywhere. In addition, the magnet center line coincides with the middle line M2 in the elevation view of FIG. 2 (a), but in the plan view of FIG. 2 (b), the apex directly above it from the intersection of the diagonal lines of the rectangle. There is only one connecting line. This one magnet center line coincides with the center line M1 of the cross-sectional triangle at this position, and ideally, a vertical magnetic field is generated in this position in the direction of the center line M1 and the magnet center line. Also, the horizontal magnetic field is ideally zero on the middle line (top line) M2 in FIG. When the plane C1 is the surface of the mounting board, each MR element 2 is individually mounted on the mounting board, so that the center of the MR element 2 is on the straight line C2 parallel to the middle line M2 (precisely the top line M2). Arrange so that When a plurality of MR elements are formed on one chip (magnetic sensor chip), the magnetic sensor chip is a plane C1, and the centers of the plurality of MR elements 2 formed on the magnetic sensor chip are on a straight line C2. The magnetic sensor chip is arranged as described above. In the case where there is one MR element, it is best to arrange the MR element on a straight line C1 orthogonal to the magnet center line in order to utilize the magnetic characteristics of the MR element.
距離ｘは、たとえば、図７に示したように、ＭＲ素子の特性曲線において磁場の変化に対してＭＲ素子の抵抗が最も効果的に変化するポイント（位置）から決定される。特に、ＭＲ素子をＫ２とＫ１との間の非飽和領域に配置すると、わずかな磁場変化によって大きな抵抗変化を発生させることができる。水平方向磁場ゼロの位置Ｙ１は、中線Ｍ２のラインとは一致しないが、そのズレ量は非常に小さく、図８に示す四角磁石の場合と比較するとその違いは歴然である。三角磁石の場合において、水平方向磁場ゼロの位置Ｙ１は三角磁石１の磁石中心Ｍ２から余りずれないので、ＭＲ素子２を多数アレイ状に配置した場合でも各ＭＲ素子に印加されるバイアス磁場の大きさは余り変化しない。従って、磁石中心Ｍ２からの距離ｘにおける各ＭＲ素子の特性曲線のバラツキもかなり小さくなる。また、多数の三角磁石においても水平方向磁場ゼロ点の位置はそれぞれの頂点（頂線）からのズレがかなり小さく、個体差が小さいので、品質の安定した磁気センサを作製できる。 For example, as shown in FIG. 7, the distance x is determined from a point (position) at which the resistance of the MR element changes most effectively with respect to the change of the magnetic field in the characteristic curve of the MR element. In particular, when the MR element is arranged in the non-saturation region between K2 and K1, a large resistance change can be generated by a slight magnetic field change. The position Y1 at which the horizontal magnetic field is zero does not coincide with the middle line M2, but the amount of deviation is very small, and the difference is obvious compared to the case of the square magnet shown in FIG. In the case of a triangular magnet, the horizontal magnetic field zero position Y1 does not deviate much from the magnet center M2 of the triangular magnet 1. Therefore, even when a large number of MR elements 2 are arranged in an array, the magnitude of the bias magnetic field applied to each MR element is large. That doesn't change much. Therefore, the variation of the characteristic curve of each MR element at the distance x from the magnet center M2 is considerably reduced. Further, even in a large number of triangular magnets, the horizontal magnetic field zero point has a very small deviation from the apex (top line) and small individual differences, so that a magnetic sensor with stable quality can be manufactured.
上記において、断面が二等辺三角形の三角磁石は磁石中心（中線）に対して磁力線分布が対称形となるので、断面が任意の三角形である三角磁石の中において水平磁場ゼロ点のズレが最も小さくなる。従って、ＭＲ素子を中線Ｍ２を挟んで逆側にもＭＲ素子を配置することもできる。このとき、ＭＲ素子を中線Ｍ２に対して対称位置に配置すると、理想的には、中線Ｍ２の両側におけるＭＲ素子特性も対称型となるので、水平方向磁場ゼロ点のズレ量が小さい三角磁石の場合は、中線Ｍ２から右側に距離ｘの直線位置にＭＲ素子を並べて配置すると、その右側のＭＲ素子の特性は左側のＭＲ素子と余り変わらない特性を得ることができる。その結果、中線の両側にＭＲ素子を並べることによって感度をさらに高めることができる。 In the above, a triangular magnet with an isosceles triangle cross section has a symmetrical magnetic field distribution with respect to the magnet center (middle line), so the horizontal magnetic field zero point deviation is the most among the triangular magnets with an arbitrary cross section. Get smaller. Accordingly, the MR element can be arranged on the opposite side of the center line M2. At this time, if the MR element is arranged at a symmetric position with respect to the middle line M2, ideally, the MR element characteristics on both sides of the middle line M2 are also symmetric, so that the amount of deviation of the horizontal magnetic field zero point is small. In the case of a magnet, when MR elements are arranged side by side at a distance x on the right side from the middle line M2, the characteristics of the MR element on the right side can obtain characteristics that are not much different from those of the left MR element. As a result, the sensitivity can be further increased by arranging MR elements on both sides of the middle line.
磁石中心（中線）に対して垂直な面Ｃ１上にＭＲ素子を配置すると最もＭＲ素子の感度を良好にできるが、多少傾いて（たとえば、１０度以下）配置しても三角磁石の場合はＭＲ素子の特性の変化は小さい。従って、ＭＲ素子と三角磁石を１つのパッケージに収納する場合において、その実装自由度が大きい。 If the MR element is arranged on the plane C1 perpendicular to the magnet center (middle line), the sensitivity of the MR element can be most improved. However, even if it is arranged slightly tilted (for example, 10 degrees or less), in the case of a triangular magnet, The change in the characteristics of the MR element is small. Therefore, when the MR element and the triangular magnet are housed in one package, the degree of freedom in mounting is great.
次に、本発明の磁気センサに用いられるバイアス永久磁石の別の実施形態を示す。
図３は、磁石の断面上部が三角形（二等辺三角形）で、断面下部が四角形（長方形）である五角形磁石と磁気抵抗効果素子の配置状態および水平方向磁場ゼロ点を示す図である。図３（ａ）は横方向断面図（立面図）であり、図３（ｂ）は水平方向透視図（平面図）である。
五角形磁石３は、三角形形状の上方がＮ極（またはＳ極）で四角形形状の下方が逆極のＳ極（またはＮ極）となるように着磁されている。三角形の上部頂点から対辺（四角形の底辺）を通る中線（垂線ともなる）Ｍ３は磁石中心線となる。五角形磁石３の断面上部は三角形状であるから、三角磁石と同様の特性を示す。従って、平面図において示すように、水平磁場ゼロ点を示す曲線Ｙ２と磁石中心線Ｍ３とのズレ量は小さい。従って、ＭＲ素子の特性バラツキも小さくなる。
図３では五角形磁石について説明したが、本発明は磁石の断面上部が三角形（好ましくは二等辺三角形）であれば、断面下部が四角形以外の形状、たとえば三角形、五角形、六角形等任意の多角形形状でも上記した効果を実現できる。このとき、三角形形状の上方がＮ極（またはＳ極）で多角形形状の下方が逆極のＳ極（またはＮ極）となるように着磁される。
Next, another embodiment of the bias permanent magnet used in the magnetic sensor of the present invention will be shown.
FIG. 3 is a diagram showing an arrangement state of a pentagonal magnet and a magnetoresistive effect element in which the upper cross section of the magnet is a triangle (isosceles triangle) and the lower cross section is a quadrangle (rectangle), and the horizontal magnetic field zero point. FIG. 3A is a transverse sectional view (elevated view), and FIG. 3B is a horizontal perspective view (plan view).
The pentagonal magnet 3 is magnetized so that the upper side of the triangular shape is an N pole (or S pole) and the lower side of the square shape is an S pole (or N pole) with a reverse polarity. A middle line (also called a perpendicular line) M3 passing from the upper vertex of the triangle to the opposite side (the bottom of the quadrangle) is the magnet center line. Since the upper section of the pentagonal magnet 3 has a triangular shape, it exhibits the same characteristics as the triangular magnet. Accordingly, as shown in the plan view, the amount of deviation between the curve Y2 indicating the horizontal magnetic field zero point and the magnet center line M3 is small. Therefore, the characteristic variation of the MR element is also reduced.
Although the pentagonal magnet has been described with reference to FIG. 3, in the present invention, if the upper cross section of the magnet is a triangle (preferably an isosceles triangle), the lower cross section is a shape other than a square, for example, an arbitrary polygon such as a triangle, pentagon, hexagon, etc. The above-described effects can be realized even in the shape. At this time, magnetization is performed so that the upper side of the triangular shape is an N pole (or S pole) and the lower side of the polygonal shape is a reverse S pole (or N pole).
次に、本発明の磁気センサをパッケージ実装したときの実施形態を示す。図４は、ＭＲ素子およびバイアス永久磁石を１つにまとめて実装した磁気センサパッケージの一例を示す図である。実装基板（プリント配線基板）１２の表面において、中央付近の所定の場所に磁気抵抗効果素子（ＭＲ素子）１１（１１−１、２）を、接着剤等を介して付着させる。実装基板１２上には必要な配線が形成されており、この配線パターンとＭＲ素子１１とをワイヤ等で接続する。また、実装基板１２の周囲には外部端子１７が備わり、この外部端子１７と実装基板の配線は導通しているので、外部からＭＲ素子１１に電圧を印加でき、また外部へ信号を出力できる。さらに、実装基板１２の表面にコトロール用ＩＣチップ（図示せず）も搭載することによって、ＭＲ素子に生ずる抵抗変化を演算処理することもできる。実装基板１２の表面上に搭載されたＭＲ素子１１やＩＣチップを保護するために、これらの素子を封止材１３で被覆する。 Next, an embodiment when the magnetic sensor of the present invention is packaged will be shown. FIG. 4 is a diagram showing an example of a magnetic sensor package in which an MR element and a bias permanent magnet are mounted together. On the surface of the mounting board (printed wiring board) 12, magnetoresistive elements (MR elements) 11 (11-1, 2) are attached to a predetermined location near the center via an adhesive or the like. Necessary wiring is formed on the mounting substrate 12, and this wiring pattern and the MR element 11 are connected by a wire or the like. In addition, an external terminal 17 is provided around the mounting substrate 12, and the wiring between the external terminal 17 and the mounting substrate is electrically connected, so that a voltage can be applied to the MR element 11 from the outside and a signal can be output to the outside. Furthermore, by mounting an IC chip for control (not shown) on the surface of the mounting substrate 12, a resistance change occurring in the MR element can be processed. In order to protect the MR element 11 and the IC chip mounted on the surface of the mounting substrate 12, these elements are covered with a sealing material 13.
実装基板１２の裏面側にバイアス永久磁石１５を配置し、非磁性で絶縁性の接着部材１６を介して実装基板（プリント配線基板）１２にバイアス永久磁石１５を付着する。バイアス永久磁石１５は三角磁石であり、その頂点Ａ側がＮ極に、その対辺（底辺）ＢＣ側がＳ極に形成されている。（これは逆でも良い。）その頂点Ａと実装基板１１との間に所定のギャップｚを持たせる。このギャップｚは、たとえば、図７に示すようなＭＲ素子の特性曲線をもとにして、三角磁石１５の頂点ＡとＭＲ素子との距離（ギャップｚ＋実装基板１２の厚さ）から決定される。また、磁石の中線Ｍ４は磁石中心線である。ＭＲ素子の中心位置は磁石の中線Ｍ４から一定距離ｘ（図２におけるｘと同じ）だけ離して実装する。このｘもたとえば、図７に示すようなＭＲ素子の特性曲線をもとにして決定される。三角磁石１５の断面形状が二等辺三角形（ＡＢ＝ＡＣ）である場合、中線Ｍ４は垂線であり、理想的には頂点Ａにおいて垂直磁場が中線Ｍ４方向に形成される。 A bias permanent magnet 15 is disposed on the back side of the mounting substrate 12, and the bias permanent magnet 15 is attached to the mounting substrate (printed wiring substrate) 12 via a nonmagnetic insulating insulating member 16. The bias permanent magnet 15 is a triangular magnet, and the apex A side is formed as an N pole, and the opposite side (base) BC side is formed as an S pole. (This may be reversed.) A predetermined gap z is provided between the vertex A and the mounting substrate 11. The gap z is determined from the distance (gap z + thickness of the mounting substrate 12) between the apex A of the triangular magnet 15 and the MR element, for example, based on the characteristic curve of the MR element as shown in FIG. . The magnet middle line M4 is a magnet center line. The center position of the MR element is mounted away from the magnet center line M4 by a fixed distance x (same as x in FIG. 2). This x is also determined based on the characteristic curve of the MR element as shown in FIG. When the cross-sectional shape of the triangular magnet 15 is an isosceles triangle (AB = AC), the middle line M4 is a perpendicular line, and ideally, a vertical magnetic field is formed at the vertex A in the direction of the middle line M4.
実装基板１２、封止材１３、端子１７、実装基板１２上にパターニングされた配線材料、ワイヤなどは、バイアス永久磁石１５の磁場への影響を極力小さくするために、非磁性材料である必要がある。実装基板１２として、紙フェノール基板、紙エポキシ基板、ガラスエポキシ基板、ポリイミド基板等の絶縁基板を使用できる。封止材１３として、エポキシ樹脂、フェノール樹脂、シリコーン樹脂、ポリイミド樹脂等を使用できる。端子１７やワイヤとして、銅、アルミニウム、金等を使用できる。接着部材１６として、エポキシ樹脂、フェノール樹脂、シリコーン樹脂、ポリイミド樹脂等を使用できる。また、実装基板等に形成される配線も銅、アルミニウム、金等の非磁性材料が望ましい。三角磁石は、ネオジウム磁石、サマリウムコバルト磁石等の希土類系磁石、フェライト磁石、アルニコ磁石等種々の磁石を使用できる。その製造方法として、ボンド磁石、焼結磁石、鋳造磁石等種々適用できる。また、ボンド磁石の成形方法として、射出成形、圧縮成形、抽出成形等種々適用できる。 The mounting substrate 12, the sealing material 13, the terminals 17, the wiring material and wires patterned on the mounting substrate 12 need to be non-magnetic materials in order to minimize the influence of the bias permanent magnet 15 on the magnetic field. is there. As the mounting substrate 12, an insulating substrate such as a paper phenol substrate, a paper epoxy substrate, a glass epoxy substrate, or a polyimide substrate can be used. As the sealing material 13, an epoxy resin, a phenol resin, a silicone resin, a polyimide resin, or the like can be used. Copper, aluminum, gold or the like can be used as the terminal 17 or the wire. As the adhesive member 16, an epoxy resin, a phenol resin, a silicone resin, a polyimide resin, or the like can be used. Also, the wiring formed on the mounting substrate or the like is preferably a nonmagnetic material such as copper, aluminum, or gold. As the triangular magnet, various magnets such as a rare earth magnet such as a neodymium magnet and a samarium cobalt magnet, a ferrite magnet, and an alnico magnet can be used. Various manufacturing methods such as bonded magnets, sintered magnets, and cast magnets can be applied. Various methods such as injection molding, compression molding, and extraction molding can be applied as a method for forming the bonded magnet.
図４に示す磁気センサパッケージのサイズの一例として、磁気センサパッケージの横幅は１５ｍｍ、高さ８ｍｍ、奥行き２０ｍｍ、断面二等辺三角形の三角磁石サイズは横幅１０ｍｍ、高さ３ｍｍ、奥行き２０ｍｍ（従って、頂角αは約１２０度）、ギャップ（ｚ）１．１ｍｍ、実装基板１２の厚みは１ｍｍ、ＭＲ素子１１のサイズは縦０．４ｍｍ、横０．４ｍｍ、厚さ０．２ｍｍ、封止材１３の厚みは１ｍｍである。また、ｘは０．１ｍｍ〜１．０ｍｍである。 As an example of the size of the magnetic sensor package shown in FIG. 4, the horizontal width of the magnetic sensor package is 15 mm, the height is 8 mm, the depth is 20 mm, and the triangular magnet size of the isosceles triangle is 10 mm in width, 3 mm in height, and 20 mm in depth. The angle α is about 120 degrees), the gap (z) is 1.1 mm, the thickness of the mounting substrate 12 is 1 mm, the size of the MR element 11 is 0.4 mm long, 0.4 mm wide, 0.2 mm thick, and the sealing material 13 The thickness is 1 mm. Moreover, x is 0.1 mm-1.0 mm.
図４ではＭＲ素子が磁石中心線の両側に２個配列しているが、これらはたとえば直列に接続され抵抗の変化量の感度を高めている。また、奥行き側は図示していないが、図２や図３に示すように多数のＭＲ素子をアレイ状に配列して、広い範囲の磁気インクパターンを読み取るようにすることもできる。ＭＲ素子は単体チップとして実装基板に搭載しているが、ＭＲ素子をまとめて１チップ化して、そのチップを実装基板に搭載しても良い。さらにコントロール用ＩＣ内にＭＲ素子を形成して、そのＩＣを実装基板に搭載しても良い。このような場合においても、ＭＲ素子１１（１１−１、２）と中線Ｍ４との距離ｘを保持するようにチップを実装する。 In FIG. 4, two MR elements are arranged on both sides of the magnet center line, but these are connected in series, for example, to increase the sensitivity of the amount of change in resistance. Although the depth side is not shown, a large number of MR elements can be arranged in an array as shown in FIGS. 2 and 3 to read a wide range of magnetic ink patterns. Although the MR element is mounted on the mounting substrate as a single chip, the MR elements may be integrated into one chip and the chip mounted on the mounting substrate. Further, an MR element may be formed in the control IC and the IC may be mounted on a mounting substrate. Even in such a case, the chip is mounted so as to maintain the distance x between the MR element 11 (11-1, 2) and the middle line M4.
三角磁石（断面形状：二等辺三角形、長さ５０ｍｍ、幅１０ｍｍ、厚さ（頂点からの高さ）３ｍｍ、頂角は約１２０°）および四角磁石（断面形状：長方形、長さ５０ｍｍ、幅１０ｍｍ、厚さ３ｍｍ）について、磁石の中心と水平磁場ゼロとの位置ズレ量を調査した。磁石の材質は共に等方性ネオジウムボンド磁石である。それぞれ３個の試料（磁石）について、磁石（ともに上側がＮ極）の直上１ｍｍの所を、磁石中心（対角線の交点）から長さ方向片側２．５ｍｍ（両側で５ｍｍ）および幅方向３．０ｍｍ（両側で６ｍｍ）の範囲の磁場を幅方向について４μｍピッチ（長さ方向は１００μｍピッチ）で測定して、幅方向の水平方向磁場ゼロのポイントを調査した。測定装置は、マグネットアナライザを用いた。 Triangular magnet (cross-sectional shape: isosceles triangle, length 50 mm, width 10 mm, thickness (height from the apex) 3 mm, apex angle is about 120 °) and square magnet (cross-sectional shape: rectangular, length 50 mm, width 10 mm) , Thickness 3 mm), the amount of positional deviation between the center of the magnet and zero horizontal magnetic field was investigated. Both magnet materials are isotropic neodymium bonded magnets. For each of the three samples (magnets), a position 1 mm directly above the magnet (both of the N poles on the upper side) is 2.5 mm on one side in the length direction (5 mm on both sides) and 3. A magnetic field in the range of 0 mm (6 mm on both sides) was measured at a pitch of 4 μm in the width direction (length direction was 100 μm pitch), and the point of zero horizontal magnetic field in the width direction was investigated. A magnet analyzer was used as a measuring device.
その結果を図５に示す。三角磁石については、頂線（頂点を結ぶ辺、長さ方向）からの水平磁場ゼロ点（線）までの距離の平均が８０μｍ（σ＝９μｍ）、四角磁石については、短辺側（幅方向）の中点を結ぶ線（磁石中心を通る）からの水平方向磁場ゼロ点（線）までの距離の平均が３３２μｍ（σ＝１１μｍ）であった。三角磁石の方が四角磁石よりもズレ量が約１／４であり、かなり小さいことが確かめられた。また、これらと同じデータを用いて水平方向磁場ゼロ点（線）の直線性について調査した。水平方向磁場ゼロ点（線）の直線性は、長さ方向に伸びる水平方向磁場ゼロ点（線）（図２におけるＹ１、および図８におけるＶ５）の幅方向における最大値と最小値の差で評価した。この差が小さいほど直線性が良い。その結果を図５に示す。三角磁石は差が約５μｍ（σ＝2.0μｍ）、四角磁石は差が２２μｍ（σ＝4.2μｍ）である。従って、三角磁石の方が四角磁石より直線性もかなり良いことが分かった。 The result is shown in FIG. For triangular magnets, the average distance from the top line (side connecting the vertices, length direction) to the horizontal magnetic field zero point (line) is 80 μm (σ = 9 μm), and for square magnets, the short side (width direction) ) The average distance from the line connecting the midpoints (through the magnet center) to the horizontal magnetic field zero point (line) was 332 μm (σ = 11 μm). The amount of deviation of the triangular magnet was about ¼ that of the square magnet, which was confirmed to be considerably small. Moreover, the linearity of the horizontal magnetic field zero point (line) was investigated using these same data. The linearity of the horizontal magnetic field zero point (line) is the difference between the maximum value and the minimum value in the width direction of the horizontal magnetic field zero point (line) extending in the length direction (Y1 in FIG. 2 and V5 in FIG. 8). evaluated. The smaller this difference, the better the linearity. The result is shown in FIG. The difference between the triangular magnets is about 5 μm (σ = 2.0 μm), and the difference between the square magnets is 22 μm (σ = 4.2 μm). Therefore, it was found that the triangular magnet has much better linearity than the square magnet.
以上説明した様に、本発明は、ＭＲ素子を用いた磁界センサにおいて、従来用いられている四角磁石の代わりに断面上部が三角形である多角柱形状の永久磁石を用いることによって、水平方向磁場ゼロ点の磁石中心線からのズレ量がかなり小さくなり、磁気特性の感度や品質が優れた磁気センサを実現できる。従って、たとえば、本発明の磁気センサを用いて磁気インク等が印刷された紙葉類の識別を行なった場合、印刷物を正確に読み取ることが可能になる。また、本発明の磁気センサに用いる水平方向磁場を検知するＭＲ素子として、トンネル磁気抵抗効果（ＴＭＲ）素子、巨大磁気抵抗効果（ＧＭＲ）素子、あるいは異方性磁気抵抗効果（ＡＭＲ）素子を用いることができる。 As described above, according to the present invention, in a magnetic field sensor using an MR element, a horizontal magnetic field zero is obtained by using a polygonal columnar permanent magnet whose upper section is a triangle instead of a conventionally used square magnet. The amount of deviation of the point from the magnet center line is considerably reduced, and a magnetic sensor with excellent sensitivity and quality of magnetic characteristics can be realized. Therefore, for example, when a paper sheet on which magnetic ink or the like is printed is identified using the magnetic sensor of the present invention, the printed matter can be read accurately. In addition, a tunnel magnetoresistive effect (TMR) element, a giant magnetoresistive effect (GMR) element, or an anisotropic magnetoresistive effect (AMR) element is used as an MR element for detecting a horizontal magnetic field used in the magnetic sensor of the present invention. be able to.
尚、明細書の各部分に記載し説明した内容を記載しなかった他の部分においても矛盾なく適用できることに関しては、当該他の部分に当該内容を適用できることは言うまでもない。さらに、上記実施形態は一例であり、要旨を逸脱しない範囲内で種々変更して実施でき、本発明の権利範囲が上記実施形態に限定されないことも言うまでもない。 In addition, it cannot be overemphasized that the said content can be applied to the said other part regarding that it can apply without contradiction also in the other part which did not describe the content described and demonstrated in each part of a specification. Furthermore, the said embodiment is an example, and can be implemented in various changes within the range which does not deviate from a summary, and it cannot be overemphasized that the right range of this invention is not limited to the said embodiment.
本発明は、水平方向磁場ゼロ点のバラツキが非常に小さいので、高性能の、非接触スイッチ、磁気ヘッド、地磁気センサ、回転センサや角度センサ等にも適用できる。 The present invention can be applied to a high-performance non-contact switch, magnetic head, geomagnetic sensor, rotation sensor, angle sensor, and the like because the variation in the horizontal magnetic field zero point is very small.
１・・・三角磁石、２・・・磁気抵抗効果素子、３・・・五角形磁石、
４・・・台形磁石、１１・・・磁気抵抗効果素子、１２・・・実装基板、
１３・・・封止材、１５・・・三角磁石、１６・・・非磁性・絶縁性材、１７・・・端子、
２１・・・四角磁石、２３・・・四角磁石、２４・・・磁気抵抗効果素子、
１０１・・・磁気センサチップ、１０２・・・永久磁石、１０３・・・磁気インク（磁性体）、１０４・・・磁気抵抗効果素子
DESCRIPTION OF SYMBOLS 1 ... Triangular magnet, 2 ... Magnetoresistive element, 3 ... Pentagonal magnet,
4 ... trapezoidal magnet, 11 ... magnetoresistive element, 12 ... mounting board,
13 ... Sealing material, 15 ... Triangular magnet, 16 ... Non-magnetic / insulating material, 17 ... Terminal,
21... Square magnet, 23... Square magnet, 24.
DESCRIPTION OF SYMBOLS 101 ... Magnetic sensor chip, 102 ... Permanent magnet, 103 ... Magnetic ink (magnetic material), 104 ... Magnetoresistive effect element
Claims (7)
The polygonal magnet according to any one of claims 1 to 6, wherein the triangular shape of the upper part of the permanent magnet has an isosceles triangle, and the upper vertex is an apex of the isosceles triangle. Magnetic sensor using
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| JP2006038770A (en) * | 2004-07-29 | 2006-02-09 | Denso Corp | Rotation detector |
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Free format text: JAPANESE INTERMEDIATE CODE: R250 |